The present invention relates to an envelope feeding apparatus for use in an electronic machine having an envelope feeding apparatus such as an electronic copying machine and an electronic photography printing machine etc., and particularly to an envelope feeding apparatus suitable for feeding a stacked state plural sheet envelopes.
Up to now, in a feeding apparatus for envelopes in an electronic copying machine and an electronic photography printing machine etc., because of many various kinds of the envelopes and many different shapes of the envelopes even in the envelopes having same sizes, it is technically difficult to attain a method of continuously feeding the plural sheet envelopes and a method of printing the envelope having a high quality under the condition of having stacked envelopes.
In particular, in a western style envelope such as an envelope (US#10, 24 lb), a flap portion of the envelope is provided to form in parallel toward a longitudinal direction of the envelopes or toward a feeding direction of the envelopes. The above western style envelope is fed to feed toward the longitudinal direction of the envelopes.
In the above case, height of the envelope at a side of the flap portion of the envelope differs from height of the envelope at a side of an anti-flap portion of the envelope. The anti-flap portion of the envelope in the present specification indicates a lower side portion of the rectangular part of the envelope. The flap portion of the envelope is continuously and integrally provided on an upper side of this rectangular part of the envelope.
Therefore, it is difficult to transfer the envelopes and further a skew state (a squint form feeding state of the envelopes) and a failure in the envelope feeding operation easily occur. As a result, so as to feed the plural sheet envelopes, in general a method for feeding the envelopes is provided where each sheet is inserted by hand of an operator through a manual envelope feeding insertion unit which is provided on a main body of the electronic copying machine.
In the electronic copying machine, since the operator himself operates the machine, it is possible to carry out the insertion for the envelope by his hand through the manual envelope feeding insertion unit.
Besides, in the electronic photography printing machine, the construction has a function in which the printing of the envelopes and/or the papers is carried out under a non-scheduled condition through a command from plural word processors or plural personal computers etc. By the above stated reasons, an envelope feeding apparatus able to feed plural sheet envelopes is indispensable to the electronic photography printing machine.
Recently envelope feeding apparatus for exclusively feeding envelopes is found here and there, however there occurs large technical problems for the envelope feeding operation because of the various shapes of the envelopes etc.
However, there are many problems to be solved for feeding the stacked envelopes, such as a low reliability of the envelope feeding operation, a skew state of a printing image due to the skew state envelope feeding operation and a folding state of a corner portion of the envelope according to deformation of the envelope etc.
So as to solve these above stated problems, a method of pressing under pressure an upper face of the stacked envelopes is frequently employed according to a member for pressing the envelope and a guide for passing through the paper (envelope). However, since the upper face of the envelope is pressed under pressure by the envelope pressing member, a resistance for feeding the envelope increases and then a force for feeding the envelope becomes insufficient.
Further, there is a case in which the envelope is pressed under pressure by the envelope pressing member having a high rigidity. In this case, when the envelope generates the moisture absorbent and the swelling, the height of the stacked envelopes differs between the side of the flap portion and the side of the anti-flap portion of the envelope.
Thereby, during the envelope feeding operation, an unbalance in the force for feeding the envelopes occurs between a left side (for example, the side of the anti-flap portion) of the envelope and a right side (for example, the side of the flap portion) of the envelope when the envelope is fed to the longitudinal direction of the envelope. As a result, there occur problems in which the skew state in the envelopes generates and the envelope feeding operation becomes impossible.
Further, in general the feeding operation of the envelopes is carried out by pressing through a paper (envelope) feeding roller under a pressing force from a lower face of the envelope.
With the above stated envelope feeding method, so as to lessen at the utmost the unbalance in the right side (for example, the flap portion side) pressing force and the left side (for example, the anti-flap portion side) pressing force, a longitudinal width of the paper (envelope) feeding roller is formed to be narrow as far as possible.
At this time, the stacked envelopes are pressed under pressure by the paper (envelope) feeding roller with the pressing force from the lower face of the envelope, then the deformation of the envelopes generates at an upper side of a tip portion of the right side of the envelope and also at an upper side of a tip portion of the left side of the envelope.
Besides, there is another type envelope feeding apparatus in which a method for feeding the envelopes is employed by stacking toward the longitudinal direction (the feeding direction) of a western style envelope. In this western style envelope, the flap portion of the envelope becomes parallel to the longitudinal direction of the envelopes.
In the above stated envelope feeding apparatus, stacked height of the envelopes differs between the side of the flap portion and the side of the anti-flap portion of the envelope and further the unbalanced condition between the right side of the envelope and the left side of the envelope occurs with respect to the paper (envelope) feeding roller, the member for pressing the envelope, and the guide for passing through the envelopes and the papers etc.
Further, when the envelope generates the moisture absorbent, it promotes the unbalance in the envelope stacked height between the side of the flap portion of the envelope and the side of the anti-flap portion of the envelope.
Consequently, the failure in the feeding operation of the envelope, the squint form feeding in the envelope, and the folding at the corner portion of the envelope at the guide portion for passing through the paper (the envelope) occur on the envelope feeding processing of the envelope feeding apparatus.
A picture image printing machine having a paper feeding apparatus as one printed document of the prior technique is disclosed, for example in Japanese patent laid-open publication No. 127077/1991.